The invention relates to an electrical contact element and to a process for its manufacture.
In electrical switching contacts and particularly when direct current is applied thereto, metal migration occurs at the contact faces, which migration causes, in known contact materials, the formation of pronounced peaks and craters which can lead to premature destruction of the contact element. This migration of material, which usually proceeds from the anode to the cathode, is a property that depends upon the structure of the contact material and upon the way the metallic components are embedded.
AuCo and PdCu alloys are known as contact materials that resist metal migration. A disadvantage of these materials is that they are required to contain a relatively large amount of noble metal, since the structure necessary for providing the required properties can be obtained only if the contact material contains a certain proportion of noble metal, as shown by the equilibrium diagrams of the alloys concerned. These alloys, resistant to metal migration, in which the metallic components are present in a thermodynamically stable ordered or heterogeneous condition as shown by the equilibrium diagram, additionally exhibit poor workability which in the case, for example, of the production of clad electrical contact rivets having a contact layer consisting of the alloy PdCu 60/40, necessitates an expensive cladding process.